Zai Lab's Zoci Offers New Hope for Devastating Brain Metastases in Lung Cancer

SAN DIEGO, CA – April 17, 2026 – A novel targeted cancer therapy has demonstrated the ability to significantly shrink tumors inside the brain for a majority of patients with an aggressive form of lung cancer, according to new data presented at the American Association for Cancer Research (AACR) Annual Meeting 2026. The drug, zocilurtatug pelitecan (Zoci) from Zai Lab, is showing unprecedented intracranial responses in patients with extensive stage small cell lung cancer (ES-SCLC) that has spread to the brain, a devastating complication with a grim prognosis.

In addition to its success in SCLC, Zoci also showed promising antitumor activity in patients with other rare and aggressive neuroendocrine carcinomas, signaling the drug’s potential to address multiple high-unmet-need cancers. The findings position Zoci as a potential breakthrough therapy and a cornerstone of Zai Lab's strategy to become a major player in the global oncology market.

A Breakthrough for Brain Metastases

For patients with ES-SCLC, the spread of cancer to the brain is a frequent and dire development that dramatically worsens their outlook. Treatment options have been severely limited, often involving whole-brain radiation that can carry significant side effects and delay systemic chemotherapy. Zai Lab's new data from a global Phase 1 trial (NCT06179069) suggests Zoci could change that paradigm.

In an analysis of patients with baseline brain metastases who had the opportunity for at least two follow-up scans, Zoci achieved an intracranial objective response rate (iORR) of 53.7%, meaning the brain tumors shrank or disappeared in over half of the 41 patients evaluated. This included seven patients who experienced a complete response, where all signs of their brain tumors vanished. The results were even more potent at what appears to be an optimal dose of 1.6 mg/kg, where the confirmed iORR climbed to an impressive 62.5%, including four complete responses.

Crucially, the drug's effectiveness was not dependent on prior treatment. Intracranial tumor reductions were observed in both patients who had previously received radiotherapy for their brain metastases (50% response rate) and those who had not (60% response rate). This suggests Zoci can penetrate the brain and effectively attack cancer cells, potentially offering a new frontline defense against brain spread.

“For patients with extensive stage small cell lung cancer who develop brain metastases... the prognosis is poor and existing therapeutic options delays systemic therapy and offer limited efficacy,” said Luis Paz-Ares, M.D. Ph.D., a senior investigator on the trial and Chair of the Medical Oncology Department at the Hospital Universitario 12 de Octubre in Madrid, Spain. “The data from these ongoing zoci clinical trials are encouraging, demonstrating not only rapid and robust responses across multiple dose cohorts, but also notable activity in patients regardless of prior intracranial radiotherapy.”

The safety profile was described as manageable, a critical factor for this heavily pretreated and vulnerable patient population. Most side effects were low grade, with the most common severe treatment-related events being manageable hematologic issues like neutropenia and anemia. Importantly, no treatment-related neurologic serious adverse events or complications related to the intracranial metastases were reported.

Targeting a Broader Spectrum of Cancers

Zoci's potential extends beyond SCLC. Zai Lab also unveiled preliminary results from a separate Phase 1b/2 study (NCT06885281) evaluating the drug in patients with extrapulmonary neuroendocrine carcinomas (epNECs). These are a group of rare, aggressive malignancies that can arise in various organs outside the lungs and for which there are no approved targeted therapies and very few effective treatments after initial chemotherapy fails.

In this difficult-to-treat population, Zoci demonstrated an overall response rate of 38.2% and a disease control rate of 55.9% among the 34 evaluable patients. This indicates that nearly four in ten patients saw their tumors shrink, and more than half had their disease stabilized or improved. These results are particularly meaningful given the lack of standard therapies for previously treated epNECs.

The findings validate the scientific rationale behind Zoci's design. The drug is an antibody-drug conjugate (ADC), a type of “smart bomb” therapy that targets a protein called Delta-like ligand 3 (DLL3).

The Science of a 'Smart Bomb' and a Global Strategy

DLL3 is highly expressed on the surface of SCLC and other neuroendocrine tumor cells but is largely absent from healthy tissues, making it an ideal target. Zoci uses an antibody to find cells with the DLL3 marker and then delivers a potent chemotherapy payload directly inside, killing the cancer cell while minimizing damage to the rest of the body. This ADC technology has evolved significantly, and Zoci's success stands in contrast to earlier-generation DLL3-targeting ADCs that failed to show sufficient efficacy.

The promising data for Zoci is a major step in Zai Lab’s strategic mission. The company plans to launch three registration-enabling studies for the drug by the end of 2026, covering second-line SCLC, first-line SCLC, and epNECs. This aggressive development plan is powered by what the company calls its integrated U.S.-China infrastructure, designed to accelerate research and clinical trials.

“The rapid progression of zoci into pivotal development, with three registration-enabling studies planned by the end of this year, is a prime example of our strategy to deliver our first global oncology launch,” said Rafael G. Amado, M.D., President, Head of Global Research and Development at Zai Lab. “The zoci data that we will present at AACR... highlight the breadth, diversity and potential of our global oncology pipeline.”

This pipeline includes other internally developed assets showcased at the conference, such as ZL-6201, an ADC targeting LRRC15 for sarcomas, and ZL-1222, a next-generation immunotherapy. The success of Zoci provides a powerful validation of Zai Lab's discovery engine and its ambition to transition from a company focused on the Chinese market to a global biopharmaceutical leader delivering its own innovative medicines worldwide.